Phantom Recipes

We use two different recipes for making phantoms. These are included below.

SEMI-COMPRESSIBLE BREAST OPTICAL PHANTOM

material: Smoothon (TM) Ecoflex liquid rubber 00-30 part A and part B
pigment: Smoothon black and white pigment

The manufacture of the phantom material is Smooth-On liquid rubber (http://www.smooth-on.com/liqrubr.htm). The model we used was Ecoflex 00-30. They now offer a newer model, 00-10, which is supposed to be softer than the 00-30 after cure. The black and white pigments we used are "Silc Pigment," from the same company (http://www.smooth-on.com/accs.htm). They are a paste-like material and very easy to mix.

Recipe:

1. Weight calculation: assuming the target phantom volume is V (ml), target mua(1/cm) and mus'(1/cm)
2. Measure V/2 part A and V/2 part B (1:1)
3. Measure black pigment  mua/6669.78*V  (in g)  (based on our recent data)
4. Measure white pigment mus/3580.19*V (in g)
5. Mix black pigment with Part A or Part B, and mixing white pigment with the other, slurring them until the pigment completely dispersed, including the corners
6. Put two parts together, mixing again, sturring for about 5 to 8 min. Then, put it under de-gaser to remove air bubbles (as long as possible but no more than 30 min under room temperature). Leave the phantom for two or 3 days to cure

HARD EPOXY RESIN MOUSE PHANTOMS

The following recipe is primarily used to make hard epoxy mouse shaped phantoms, with embedded inclusions for fluorophores. But the recipe can generally be used to mold to any shape.

The original mouse mold was created from a mouse phantom based on a sacrificed real mouse (Advanced research Technologies). The negative mold was made of smoothon liquid rubber.

The mold for the phantom consisted of a two-part epoxy resin and hardener mixture (Douglas & Sturgess Inc., San Francisco CA; http://www.artstuf.com/). Specifically, epoxy resin 7132 and Hardner 2001 were used. A 2 parts resin to 1 part hardener mixture (by weight) combination yields a sold phantom after less than 12 hours of curing.

Once the epoxy and hardener are weighed and mixed, a combination of TiO2 (paint) and ink is added to the resin, to achieve desired background optical properties. Any residual air bubbles are then removed using a vaccum pump. Inclusions (cavities) can be created inside the phantom by positioning low-melting-point agar beads (5 mm diameter) that were originally cast in a spherical negative mold, using pairs of syringe needles. The epoxy mixture is then poured into the negative mold and simply left to cure for about 12 hours. Once cured, the negative mold was removed along with the needles. Fresh needles were then attached along with polypropylene tubing, enabling dynamic injection of fluorophores into the inclusions.